Half:Life baby, the king of shooters.

Timesplitters 2 as well.

Killzone 2

Killzone 2 would be my pick for best FPS ever made.

yes

Half Life 1 with mods > Quake III > Unreal Tournament >>>>>> everything else.

1)KZ2

2)CoD4

3)Doom1/2

Wow, I'm amazed you all got the answer wrong.

The best FPS is Team Fortress 2.

/thread

The best FPS ever is the first Half Life.

Besides obvious choices (HL, COD, GE007, PD etc.), already mentioned and mostly multiplayer-driven current gen games. I'd say the followings are good examples of what I call interesting single player experience from first-person (though many of them aren't strictly FPSs): - Aliens versus Predator - Deus Ex - Marathon - Metroid Prime - No One Lives Forever - Pathways into Dakness - Star Wars: Dark Forces - System Shock. Some of them you may find dated, not only dated visuals, but dated gameplay... nevertheless at least half of the list is still relevant and fresh gameplay wise.